一、三文鱼发病前一般有如下征兆1.离群鱼或游于水面、排水部的鱼或在池壁、池底缓游的鱼增多。2.游泳方式异常，出现突进式、旋回式、竖直上下式、曲体或侧体游动或擦磨活动。3.活泼度、集群性下降，摄饵反应迟钝，摄饵量减少。4.体色发暗、变黑或呈灰黄色。5.体表局部浮肿或 First, the salmon before the onset of symptoms generally have the following symptoms: 1. Outlying fish or swim in the water, the Department of fish drainage or in the pool wall, the bottom of the fish swimming slowly. 2. Abnormal swimming, there are sudden, cyclical, vertical up and down, curved or lateral swimming or rubbing activities. 3. Activity, clustering decreased, unresponsive bait, bait decreased. Body color dark, dark or grayish yellow. 5. Body surface swelling or local